In recent years there has been an increasing interest in metal alloys which are not only hard but are of relatively light weight. Such materials include, for example, titanium-aluminum alloys and others which have a highly crystalline structure and are difficult to roll. Attempts to roll such alloys may embrittle them, cause the formation of stress cracks and likewise alter the structural soundness of the product.
Other shaping methods generally cannot be used in a practical manner for the fabrication of large-size objects. For example, such materials cannot be turned or milled effectively because of their hardness and other shaping methods than electric-discharge machining, for example, can be impractical or unsatisfactory.
Electric-discharge machining may not be able to economically create desired shapes in large objects, especially if complex configurations such as fuselage, air foil, air guide and vane configurations are involved.
Accordingly, at the present time there is no common commercial and technologically acceptable way of forming shaped bodies from TiAl.sub.3 and similar hard and difficult-to-roll alloys.
Mention should be made of the fact that in my copending application Ser. No. 941,185 filed Dec. 12, 1986 and now U.S. Pat. No. 4,828,934 and the patents and applications mentioned therein, I have described a low-temperature arc vapor deposition method of depositing metals and metal compounds or metal alloys-upon a variety of substrates with high-bonding strength and unique properties of the applied layers. The technique has been used effectively to create a variety of metal structures, to produce ceramics, to coat ceramics and to create compounds and compositions of various formations upon a variety of substrates.
Essentially the technique involves striking an arc between electrodes including at least one electrode of a material to be deposited on a substrate, in an evacuated space, and causing vaporization of the electrode material with the low-voltage, high-current arc which then results.